1. Technical Field
The present invention relates to an image forming apparatus.
2. Related Art
As an image forming apparatus which performs color printing, there is a tandem type apparatus in which image forming sections (photosensitive members, exposing devices, and the like) that transfer toner images of colors (Y (yellow), M (magenta), C (cyan), and K (black)) to a sheet are provided respectively for the colors.
In the tandem type image forming apparatus, the respective image forming sections perform a printing operation on one sheet to form a color image configured by toner images of the four colors.
When transfer timings of the image forming sections are caused to be delicately deviated from one another by a temperature rise in the apparatus, a temporal change, or the like, therefore, so-called misregistration in which only a specific color is printed while being deviated in one image occurs.
As a registration adjusting technique for correcting the misregistration, known is a technique in which each image forming section forms a registration adjustment patch (hereinafter, referred to as regi adjustment patch) configured by a toner image on a transfer belt, the regi adjustment patches for the colors on the transfer belt are detected by a sensor, the amount of deviating from a reference position is calculated, and the writing timing of the image forming section or the like is corrected so as to eliminate the misregistration amount.